Some states have promulgated traffic laws requiring the head lights and tail lights to be turned on when driving in the rain. The advantages associated with providing circuitry in an automobile for linking the windshield wiper and headlight controls, so that the headlights are turned on automatically with the windshield wipers are pointed out in the following U.S. Pats. Nos. 3,500,119; 3,519,837; 3,600,596; and 3,824,405.
The techniques utilized in these aforementioned patents for linking the windshield wiper and headlights have not been sufficiently simple to enable easy conversion of existing vehicles since they have generally involved the provision of additional circuitry associated with the usual windshield wiper switch.